The present invention relates to the production of a rotor, containing permanent magnets, of a synchronous machine, which rotor has a core of ferromagnetic steel, on which and connected to the core of which are permanent magnets which in turn are surrounded by an outer cylinder of a non-magnetizable steel, and which rotor has closure plates of a non-magnetizable steel with a stub shaft.
In the operation of a permanent magnet excited synchronous machine, the permanent magnets seated on the rotor are exposed to considerable centrifugal forces, with the consequence that they tend to come loose from the rotor. Shrinking on a metallic cylinder over the magnets seated on the rotor is known. The permanent magnets, as is well known, consist of a brittle material, so that cracks and breaks are already practically unavoidable when shrinking the cylinder on. These permanent magnets moreover consist of a material which is very susceptible to corrosion and have to be wholly surrounded by a protective layer which is also durable during operation. The application of such protective layers on the one hand requires much work and on the other hand, in known constitutions, leaves broken places on the permanent magnets, occurring on (a first) run-up to operating rotational speed, without any protection against corrosion. It is known that the permanent magnets have to be ground to obtain correct dimensions, This grinding also requires much work.
The invention has as its object to provide a process of production of a permanent magnet excited synchronous machine, and a rotor produced by this process, according to which the permanent magnets are mounted hydrostatically, so to speak, and furthermore the permanent magnets also have no unprotected surfaces even after sustaining fractures after first running up to operating speed.
The process according to the invention is distinguished in that the core is constituted with an internal space, and a resin mass is introduced into the internal space and is supplied to the region of the permanent magnets by centrifuging the rotor, a hardening of the resin mass then taking part in the said region. The rotor produced by the process according to the invention is characterized by a core of ferromagnetic steel and an internal space extending axially, the permanent magnets being arranged on the said core and being surrounded by an outer cylinder of non-magnetizable material, the said rotor having closure disks of non-magnetizable steel at both ends with stub shafts, which are positively connected to the core and at least frictionally connected to the outer cylinder, and that all the cavities in the region of the permanent magnets are filled with a resin mass.
The advantages attained with the invention are in particular that the permanent magnets are completely surrounded by the resin mass and thus in actual fact are hydrostatically mounted, so that they are secured against a displacement due to centrifugal forces; and that the resin mass is still flowable during the first running-up to speed, so that it fills the cracked regions of the permanent magnets appearing during this period, and covers the additionally resulting bare surfaces of the permanent magnets.